The present invention relates to a method for disassembly of a rotor, in particular the first rotor of a gas turbine, a method for assembly of such a rotor as well as a tool for securing at least one additional rotor in such assembly or disassembly and a gas turbine particularly suitable for the same.
U.S. Pat. No. 7,186,078 B2, for example, discloses a low-pressure gas turbine having a housing and a channel, in which several rotors are arranged one after the other to withdraw energy from a gas.
The outside diameter of the channel and the rotors arranged in succession increase in the direction of flow.
According to in-house practice for assembly, the front rotor having the smallest outside diameter is first inserted into the conical channel from the rear against the direction of flow, then another rotor having a larger outside diameter, etc., until the most-rear rotor having the largest outside diameter is inserted. For disassembly of the front rotor, all the rear rotors must first be disassembled in the opposite order accordingly in a tedious operation before the front rotor can finally be pulled from the conical channel toward the rear.
On the other hand, the front rotor is usually exposed to the highest mechanical and/or thermal stresses, so that it must be disassembled most often for inspection purposes and/or maintenance purposes.
It is one object of an embodiment of the present invention to improve the inspection and/or maintenance of a gas turbine.
One aspect of the present invention relates to a method for disassembly of a rotor of a gas turbine. Another aspect relates to a gas turbine which is particularly suitable for this. Accordingly, the following explanations equally apply to a method and/or a gas turbine according to one aspect and/or advantageous embodiments of the present invention.
The gas turbine may be in particular a low-pressure gas turbine and/or turbine stage, preferably an aircraft engine, and may have a housing and a channel, in which the rotor is arranged and which diverges in a direction of flow. For a more compact presentation, in the present case a housing part of a multipart overall housing is also referred to simply as the housing.
A contour, in particular a diameter of the channel, may become wider in the direction of flow, in particular at least essentially monotonically and/or in increments.
The rotor to be disassembled is arranged in the channel and one or more additional rotors may be arranged in one embodiment. A guide baffle may be arranged upstream and/or downstream from one or more rotors, in particular between neighboring rotors, in the direction of flow.
In a refinement of the invention, the rotor to be disassembled is the first rotor, i.e., the most upstream rotor in the direction of flow and the additional rotors are the rear rotors, i.e., the more downstream rotors. Accordingly, in the present case, an axial upstream position in the direction of flow is understood to be the forward position and/or front position, while a downstream axial position in the direction of flow is understood to be the rear position, i.e., at the back.
In one embodiment, the rotor to be disassembled has a rotor disk plus one or more rotor blades distributed in the circumferential direction. The rotor blades may be attached detachably to the rotor disk, in particular in a form-fitting manner, preferably by means of profiled blade feet, or it may be attached permanently, in particular in a physically bonded manner, preferably designed to be integral with the rotor disk, i.e., as a so-called BLISK. In one embodiment, the rotor blades have outer casings on the outside radially, which together form an outer ring, while in another embodiment, the rotor blades are without an outer casing.
In one embodiment, the outside contour, in particular the outside diameter of the rotor blades of the rotor becomes larger, in particular that of an outside ring of the rotor in the direction of flow.
In one embodiment, the outer ring may have one or more radial flanges and/or sealing tips which are spaced a distance apart axially and extend radially outward. In one refinement, an outside diameter of a front radial flange is smaller than an outside diameter of a rear radial flange. In one embodiment, the maximum outside diameter of the rotor to be disassembled lies in its rear half in the direction of flow.
An outer sealing ring is arranged between the rotor and the housing. Accordingly, in one embodiment, the outer sealing ring of a gas turbine according to one aspect of the present invention is a first and/or most-forward and/or most-upstream outer sealing ring in the direction of flow.
The outer sealing ring may be detachably attached to the channel and/or housing. In particular a rear axial flange of the outer sealing ring in the direction of flow may be suspended in a corresponding groove in the housing, which, in one refinement, may be formed by a guide baffle attached to the housing. In one embodiment, the outer sealing ring has an abradable coating and/or a honeycomb seal on the inside radially and/or facing the rotor.
In one embodiment, an internal contour, in particular an inside diameter of the outer sealing ring, becomes wider in the direction of flow, in particular monotonically, preferably in one or more steps. In one refinement of the invention, a shoulder on the inside surface of the outer sealing ring to be installed is opposite a radial flange of an outer ring of the rotor to be dismantled, another shoulder being opposite another radial flange of the outer ring.
In one embodiment, a minimum inside diameter of the outer sealing ring, in particular toward the front, is smaller than the maximum outside diameter of the rotor, in particular as the most-rear outside diameter of an outer ring, preferably as the outside diameter of a radial flange (the farthest to the rear) of the outer ring.
According to one aspect of the present invention, the rotor to be disassembled is disassembled and/or displaced axially against the direction of flow, in particular being shifted out of the housing toward the front.
To do so, in one embodiment, first the outer sealing ring, whose (smaller) minimum inside diameter would come in conflict with the (larger) maximum outside diameter in the event of shifting of the rotor, is displaced axially against the direction of flow, in particular being shifted forward out of the housing. Next the rotor itself may also be displaced axially against the direction of flow, in particular being shifted forward out of the housing.
According to one aspect of the present invention, a rotor, in particular the front rotor, can be disassembled directly in this way, in particular without disassembly of rear rotors. The inspection and/or maintenance, in particular replacement of the rotor can be simplified in this way.
If the maximum outside diameter of the outer sealing ring is smaller than the minimum (inside) diameter of the section of the channel situated in front of it in the direction of shifting, then the outer sealing ring may easily be displaced axially out of the channel against the direction of flow. However, if the minimum (inside) diameter of the section of the channel situated in front of it in the direction of shifting is smaller, this is not the case. Therefore, according to one aspect of the present invention, the outer sealing ring, whose maximum outside diameter is larger than a minimum (inside) diameter of the channel, is divided into two or more, preferably at least 16, in particular at least 32, parts in the circumferential direction. Then the outer sealing ring parts may be shifted radially inward and/or toward an axis of rotation of the gas turbine and may also be passed by the smaller inside diameter of the channel in this way.
This radial shift inward and the axial shift in the direction against the direction of flow may be superimposed at least partially and/or in some sections. In one embodiment, this can minimize the effort and/or movement space required for execution against the direction of flow. Additionally or alternatively, outer sealing ring parts may also be shifted strictly radially and/or strictly axially, at least in some sections and/or partially. For example, the outer sealing ring or outer sealing ring parts may first be shifted by an axial path length against the direction of flow, for example, up to blocking by the channel. Then the outer sealing ring parts may be shifted radially inward or with the superpositioning of another axial shift radially inward, so that they can pass by the channel.
In one embodiment, the outer sealing ring parts are also tilted in addition to their axial and/or radial shift, in particular to release them from a circumferential groove in the housing prior to being displaced axially. In a preferred embodiment, however, the outer sealing ring parts may be, at least essentially, axially tilt-free and may optionally be shifted radially and/or need not be tilted in advance for the axial shift. It is possible in particular to provide that the outer sealing ring and/or the outer sealing ring parts are displaced axially in a tilt-free manner at first.
In this regard, according to one aspect of the present invention in particular, the outer sealing ring is attached to the housing in a non-form-fitting manner with frictional locking, detachably and against the direction of flow. In the present case, this is understood in particular to mean that the outer sealing ring is attached to the housing in a releasable and frictionally locked manner, such that it can be displaced axially, in particular microscopically, and/or by at least 5 mm, after releasing the friction locking against the direction of flow without a radial shoulder of a friction contact surface of the housing opposing this friction-locking connection to the outer sealing ring, in particular a wall of a circumferential grove. The outer sealing ring may be attached to the housing detachably and in a friction-locking manner, by a one-piece or multipiece stretched so-called C ring (“C clip”) in one embodiment.
In one refinement of the invention, however, the outer sealing ring may be secured on the housing in a form-fitting manner in the direction of flow, in particular by a one-sided shoulder, such that in the present case a circumferential groove is referred to as a two-sided shoulder in contrast with such a one-sided shoulder.
In one embodiment, the outer sealing ring is secured on the housing in a form-fitting manner in the circumferential direction. To do so, in another refinement, the outer sealing ring may have one or more radial protrusions, which extend radially outward from an outer circumferential surface of the outer sealing ring for friction locking with a radially opposed inner circumferential surface of the housing and may engage in corresponding axial grooves in the housing which may be arranged in particular on an end face of the housing that is at the front in the direction of flow. Additionally or alternatively, the housing may have one or more radial protrusions which extend radially inward from an inner circumferential surface of the housing for friction locking with a radially opposite outer circumferential surface of the outer sealing ring and may engage in corresponding axial grooves in the outer sealing ring, which may be arranged in particular on an end face of the outer sealing ring that is at the rear in the direction of flow. The extent of the radial protrusion in the circumferential direction may be smaller than, equal to, or larger than the distance in the circumferential direction between two walls that are adjacent in the circumferential direction of two grooves that are adjacent in the circumferential direction.
Accordingly, in one embodiment, the outer sealing ring and the housing may be attached to one another in a friction-locking manner and may be secured not in a friction-locking manner only in the circumferential direction and/or in the flow direction but not secured in the direction against the direction of flow, in particular not by means of a circumferential groove.
In one embodiment, an initial tilting of the outer sealing ring and/or outer sealing ring parts may be prevented in this way by the fact that these are initially displaced axially in a direction against the direction of flow. In this way, it is advantageously possible to reduce the sealing gap between the outer sealing ring and the rotor, which must otherwise be enlarged to permit tilting, but that would negatively impact the sealing effect.
Depending on the structural design, the rotor to be disassembled may oppose a radial shifting of the outer sealing ring parts in its assembly position. Therefore in particular in one embodiment of the present invention, the rotor is shifted first axially in the direction of flow and/or before the radial shifting of the outer sealing ring parts. In this way, in one embodiment, (additional) space for radial shifting of the outer sealing ring parts may be made available toward the inside radially, optionally with superpositioning of an axial shifting against the direction of flow. Likewise, however, it is also possible to provide for the outer sealing ring and/or the outer sealing ring parts to be initially displaced axially in a direction against the direction of flow without first displacing or having to displace the rotor in the direction of flow.
The housing may be connected at its front end face to a connecting flange. This connecting flange may in particular be part of a high-pressure turbine or the like, which is upstream from a low-pressure turbine, or may be part of a connecting piece thereto. Likewise, the connecting flange may also be part of a transport cover for closing the channel or the like.
Accordingly, in one embodiment of the present invention, a connecting flange which is connected to the housing and whose inside diameter facing the rotor is smaller than the maximum outside diameter of the outer sealing ring is released from the housing before the axial shifting of the outer sealing ring in the direction against the direction of flow. A connecting flange without a through-opening is also referred to as a connecting flange to this extent, its inside diameter facing the rotor being equal to zero and thus smaller than the maximum outside diameter of the outer sealing ring.
In one embodiment of the present invention, a connection of the outer sealing ring to the housing, in particular a C ring, in particular a friction-locking connection is released prior to the axial shifting of the outer sealing ring in the direction against the direction of flow.
In one embodiment, one or more additional rotors of the gas turbine may be supported radially and/or axially by means of the rotor to be disassembled. In disassembly of the rotor without prior disassembly of the additional rotors, this support and/or bearing is omitted. Accordingly, in one embodiment, one or more additional rotors of the gas turbine is/are secured otherwise prior to the axial shifting of the rotor to be disassembled in the direction against the direction of flow. To do so, they may in particular be secured by a releasable tool that is secured on at least one of the additional rotors detachably in particular in a friction-locking and/or form-fitting manner and is in turn supported. The tool may be supported on the housing of the gas turbine in particular, preferably in a friction-locking and/or form-fitting manner.
Accordingly, one aspect of the present invention relates to a tool for securing one or more additional rotors in assembly or disassembly of a rotor of a gas turbine according to one of the methods described here, in particular its use for securing one or more additional rotors in assembly or disassembly of a rotor of a gas turbine according to one of the methods described here. In one embodiment, the tool has fasteners for form-fitting and/or friction-locking attachment to the housing and/or to one or more additional rotors of the gas turbine. The fasteners may in particular have one or more recesses and/or protrusions for form-fitting attachment and/or one or more tension devices in particular screws for friction-locking attachment. In one embodiment, the tool has a radial flange for attachment to a housing and an axial web to reach through one or more additional rotors radially and be attached to them.
One aspect of the present invention relates to the initial assembly or re-assembly of the rotor, in particular the front rotor in the direction of flow in the front into the housing. This assembly may essentially take place in the opposite order from the disassembly mentioned first so that reference is made thereto in addition.
Accordingly, in one embodiment, first the rotor to be assembled is displaced axially in the direction of flow, in particular into the housing and then the outer sealing ring is displaced axially in the direction of flow, in particular into the housing.
In one embodiment, parts of the outer sealing ring are shifted radially toward the housing of the gas turbine and then joined together to form the outer sealing ring, in particular being clamped in the circumferential direction and/or connected in a form-fitting manner. This radial shifting may be superimposed on axial shifting of the entire outer sealing ring or the outer sealing ring parts at least in sections and/or in phases.
In one embodiment, the rotor is displaced axially against the direction of flow after the radial shifting of the outer sealing ring parts. Space for movement can occasionally be created for the radial shift in this way.
In one embodiment, after the axial shifting of the outer sealing ring in the direction of flow, a connecting flange whose inside diameter facing the rotor is smaller than the maximum outside diameter of the outer sealing ring is connected to the housing, preferably detachably. Additionally or alternatively, after the axial shifting of the outer sealing ring in the direction of flow, the outer sealing ring is attached to the housing, preferably detachably, and/or a connection of the outer sealing ring to the housing may be closed. A C ring in particular may be attached to clamp the outer sealing ring and the housing in a friction-locking manner.
As explained above, one or more additional rotors may be secured during assembly, in particular by a detachable tool. In particular after the rotor to be assembled has been assembled, in particular being supported and/or mounted on the housing, a corresponding attachment and/or the tool may be released.
Additional advantageous refinements of the present invention are derived from the dependent claims and the following description of preferred embodiments.